drivers/mtd/mtdchar.c - LeafOS-Devices/android_kernel_samsung_exynos9820 - Gitiles

 /*
  * Character-device access to raw MTD devices.
  *
  */

 #include <linux/device.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/smp_lock.h>
 #include <linux/backing-dev.h>
 #include <linux/compat.h>
 #include <linux/mount.h>

 #include <linux/mtd/mtd.h>
 #include <linux/mtd/compatmac.h>

 #include <asm/uaccess.h>

 #define MTD_INODE_FS_MAGIC 0x11307854
 static struct vfsmount *mtd_inode_mnt __read_mostly;

 /*
  * Data structure to hold the pointer to the mtd device as well
  * as mode information ofr various use cases.
  */
 struct mtd_file_info {
 	struct mtd_info *mtd;
 	struct inode *ino;
 	enum mtd_file_modes mode;
 };

 static loff_t mtd_lseek (struct file *file, loff_t offset, int orig)
 {
 	struct mtd_file_info *mfi = file->private_data;
 	struct mtd_info *mtd = mfi->mtd;

 	switch (orig) {
 	case SEEK_SET:
 		break;
 	case SEEK_CUR:
 		offset += file->f_pos;
 		break;
 	case SEEK_END:
 		offset += mtd->size;
 		break;
 	default:
 		return -EINVAL;
 	}

 	if (offset >= 0 && offset <= mtd->size)
 		return file->f_pos = offset;

 	return -EINVAL;
 }


 static int mtd_open(struct inode *inode, struct file *file)
 {
 	int minor = iminor(inode);
 	int devnum = minor >> 1;
 	int ret = 0;
 	struct mtd_info *mtd;
 	struct mtd_file_info *mfi;
 	struct inode *mtd_ino;

 	DEBUG(MTD_DEBUG_LEVEL0, "MTD_open\n");

 	/* You can't open the RO devices RW */
 	if ((file->f_mode & FMODE_WRITE) && (minor & 1))
 		return -EACCES;

 	lock_kernel();
 	mtd = get_mtd_device(NULL, devnum);

 	if (IS_ERR(mtd)) {
 		ret = PTR_ERR(mtd);
 		goto out;
 	}

 	if (mtd->type == MTD_ABSENT) {
 		put_mtd_device(mtd);
 		ret = -ENODEV;
 		goto out;
 	}

 	mtd_ino = iget_locked(mtd_inode_mnt->mnt_sb, devnum);
 	if (!mtd_ino) {
 		put_mtd_device(mtd);
 		ret = -ENOMEM;
 		goto out;
 	}
 	if (mtd_ino->i_state & I_NEW) {
 		mtd_ino->i_private = mtd;
 		mtd_ino->i_mode = S_IFCHR;
 		mtd_ino->i_data.backing_dev_info = mtd->backing_dev_info;
 		unlock_new_inode(mtd_ino);
 	}
 	file->f_mapping = mtd_ino->i_mapping;

 	/* You can't open it RW if it's not a writeable device */
 	if ((file->f_mode & FMODE_WRITE) && !(mtd->flags & MTD_WRITEABLE)) {
 		iput(mtd_ino);
 		put_mtd_device(mtd);
 		ret = -EACCES;
 		goto out;
 	}

 	mfi = kzalloc(sizeof(*mfi), GFP_KERNEL);
 	if (!mfi) {
 		iput(mtd_ino);
 		put_mtd_device(mtd);
 		ret = -ENOMEM;
 		goto out;
 	}
 	mfi->ino = mtd_ino;
 	mfi->mtd = mtd;
 	file->private_data = mfi;

 out:
 	unlock_kernel();
 	return ret;
 } /* mtd_open */

 /*====================================================================*/

 static int mtd_close(struct inode *inode, struct file *file)
 {
 	struct mtd_file_info *mfi = file->private_data;
 	struct mtd_info *mtd = mfi->mtd;

 	DEBUG(MTD_DEBUG_LEVEL0, "MTD_close\n");

 	/* Only sync if opened RW */
 	if ((file->f_mode & FMODE_WRITE) && mtd->sync)
 		mtd->sync(mtd);

 	iput(mfi->ino);

 	put_mtd_device(mtd);
 	file->private_data = NULL;
 	kfree(mfi);

 	return 0;
 } /* mtd_close */

 /* FIXME: This _really_ needs to die. In 2.5, we should lock the
    userspace buffer down and use it directly with readv/writev.
 */
 #define MAX_KMALLOC_SIZE 0x20000

 static ssize_t mtd_read(struct file *file, char __user *buf, size_t count,loff_t *ppos)
 {
 	struct mtd_file_info *mfi = file->private_data;
 	struct mtd_info *mtd = mfi->mtd;
 	size_t retlen=0;
 	size_t total_retlen=0;
 	int ret=0;
 	int len;
 	char *kbuf;

 	DEBUG(MTD_DEBUG_LEVEL0,"MTD_read\n");

 	if (*ppos + count > mtd->size)
 		count = mtd->size - *ppos;

 	if (!count)
 		return 0;

 	/* FIXME: Use kiovec in 2.5 to lock down the user's buffers
 	   and pass them directly to the MTD functions */

 	if (count > MAX_KMALLOC_SIZE)
 		kbuf=kmalloc(MAX_KMALLOC_SIZE, GFP_KERNEL);
 	else
 		kbuf=kmalloc(count, GFP_KERNEL);

 	if (!kbuf)
 		return -ENOMEM;

 	while (count) {

 		if (count > MAX_KMALLOC_SIZE)
 			len = MAX_KMALLOC_SIZE;
 		else
 			len = count;

 		switch (mfi->mode) {
 		case MTD_MODE_OTP_FACTORY:
 			ret = mtd->read_fact_prot_reg(mtd, *ppos, len, &retlen, kbuf);
 			break;
 		case MTD_MODE_OTP_USER:
 			ret = mtd->read_user_prot_reg(mtd, *ppos, len, &retlen, kbuf);
 			break;
 		case MTD_MODE_RAW:
 		{
 			struct mtd_oob_ops ops;

 			ops.mode = MTD_OOB_RAW;
 			ops.datbuf = kbuf;
 			ops.oobbuf = NULL;
 			ops.len = len;

 			ret = mtd->read_oob(mtd, *ppos, &ops);
 			retlen = ops.retlen;
 			break;
 		}
 		default:
 			ret = mtd->read(mtd, *ppos, len, &retlen, kbuf);
 		}
 		/* Nand returns -EBADMSG on ecc errors, but it returns
 		 * the data. For our userspace tools it is important
 		 * to dump areas with ecc errors !
 		 * For kernel internal usage it also might return -EUCLEAN
 		 * to signal the caller that a bitflip has occured and has
 		 * been corrected by the ECC algorithm.
 		 * Userspace software which accesses NAND this way
 		 * must be aware of the fact that it deals with NAND
 		 */
 		if (!ret || (ret == -EUCLEAN) || (ret == -EBADMSG)) {
 			*ppos += retlen;
 			if (copy_to_user(buf, kbuf, retlen)) {
 				kfree(kbuf);
 				return -EFAULT;
 			}
 			else
 				total_retlen += retlen;

 			count -= retlen;
 			buf += retlen;
 			if (retlen == 0)
 				count = 0;
 		}
 		else {
 			kfree(kbuf);
 			return ret;
 		}

 	}

 	kfree(kbuf);
 	return total_retlen;
 } /* mtd_read */

 static ssize_t mtd_write(struct file *file, const char __user *buf, size_t count,loff_t *ppos)
 {
 	struct mtd_file_info *mfi = file->private_data;
 	struct mtd_info *mtd = mfi->mtd;
 	char *kbuf;
 	size_t retlen;
 	size_t total_retlen=0;
 	int ret=0;
 	int len;

 	DEBUG(MTD_DEBUG_LEVEL0,"MTD_write\n");

 	if (*ppos == mtd->size)
 		return -ENOSPC;

 	if (*ppos + count > mtd->size)
 		count = mtd->size - *ppos;

 	if (!count)
 		return 0;

 	if (count > MAX_KMALLOC_SIZE)
 		kbuf=kmalloc(MAX_KMALLOC_SIZE, GFP_KERNEL);
 	else
 		kbuf=kmalloc(count, GFP_KERNEL);

 	if (!kbuf)
 		return -ENOMEM;

 	while (count) {

 		if (count > MAX_KMALLOC_SIZE)
 			len = MAX_KMALLOC_SIZE;
 		else
 			len = count;

 		if (copy_from_user(kbuf, buf, len)) {
 			kfree(kbuf);
 			return -EFAULT;
 		}

 		switch (mfi->mode) {
 		case MTD_MODE_OTP_FACTORY:
 			ret = -EROFS;
 			break;
 		case MTD_MODE_OTP_USER:
 			if (!mtd->write_user_prot_reg) {
 				ret = -EOPNOTSUPP;
 				break;
 			}
 			ret = mtd->write_user_prot_reg(mtd, *ppos, len, &retlen, kbuf);
 			break;

 		case MTD_MODE_RAW:
 		{
 			struct mtd_oob_ops ops;

 			ops.mode = MTD_OOB_RAW;
 			ops.datbuf = kbuf;
 			ops.oobbuf = NULL;
 			ops.len = len;

 			ret = mtd->write_oob(mtd, *ppos, &ops);
 			retlen = ops.retlen;
 			break;
 		}

 		default:
 			ret = (*(mtd->write))(mtd, *ppos, len, &retlen, kbuf);
 		}
 		if (!ret) {
 			*ppos += retlen;
 			total_retlen += retlen;
 			count -= retlen;
 			buf += retlen;
 		}
 		else {
 			kfree(kbuf);
 			return ret;
 		}
 	}

 	kfree(kbuf);
 	return total_retlen;
 } /* mtd_write */

 /*======================================================================

     IOCTL calls for getting device parameters.

 ======================================================================*/
 static void mtdchar_erase_callback (struct erase_info *instr)
 {
 	wake_up((wait_queue_head_t *)instr->priv);
 }

 #ifdef CONFIG_HAVE_MTD_OTP
 static int otp_select_filemode(struct mtd_file_info *mfi, int mode)
 {
 	struct mtd_info *mtd = mfi->mtd;
 	int ret = 0;

 	switch (mode) {
 	case MTD_OTP_FACTORY:
 		if (!mtd->read_fact_prot_reg)
 			ret = -EOPNOTSUPP;
 		else
 			mfi->mode = MTD_MODE_OTP_FACTORY;
 		break;
 	case MTD_OTP_USER:
 		if (!mtd->read_fact_prot_reg)
 			ret = -EOPNOTSUPP;
 		else
 			mfi->mode = MTD_MODE_OTP_USER;
 		break;
 	default:
 		ret = -EINVAL;
 	case MTD_OTP_OFF:
 		break;
 	}
 	return ret;
 }
 #else
 # define otp_select_filemode(f,m)	-EOPNOTSUPP
 #endif

 static int mtd_do_writeoob(struct file *file, struct mtd_info *mtd,
 	uint64_t start, uint32_t length, void __user *ptr,
 	uint32_t __user *retp)
 {
 	struct mtd_oob_ops ops;
 	uint32_t retlen;
 	int ret = 0;

 	if (!(file->f_mode & FMODE_WRITE))
 		return -EPERM;

 	if (length > 4096)
 		return -EINVAL;

 	if (!mtd->write_oob)
 		ret = -EOPNOTSUPP;
 	else
 		ret = access_ok(VERIFY_READ, ptr, length) ? 0 : -EFAULT;

 	if (ret)
 		return ret;

 	ops.ooblen = length;
 	ops.ooboffs = start & (mtd->oobsize - 1);
 	ops.datbuf = NULL;
 	ops.mode = MTD_OOB_PLACE;

 	if (ops.ooboffs && ops.ooblen > (mtd->oobsize - ops.ooboffs))
 		return -EINVAL;

 	ops.oobbuf = kmalloc(length, GFP_KERNEL);
 	if (!ops.oobbuf)
 		return -ENOMEM;

 	if (copy_from_user(ops.oobbuf, ptr, length)) {
 		kfree(ops.oobbuf);
 		return -EFAULT;
 	}

 	start &= ~((uint64_t)mtd->oobsize - 1);
 	ret = mtd->write_oob(mtd, start, &ops);

 	if (ops.oobretlen > 0xFFFFFFFFU)
 		ret = -EOVERFLOW;
 	retlen = ops.oobretlen;
 	if (copy_to_user(retp, &retlen, sizeof(length)))
 		ret = -EFAULT;

 	kfree(ops.oobbuf);
 	return ret;
 }

 static int mtd_do_readoob(struct mtd_info *mtd, uint64_t start,
 	uint32_t length, void __user *ptr, uint32_t __user *retp)
 {
 	struct mtd_oob_ops ops;
 	int ret = 0;

 	if (length > 4096)
 		return -EINVAL;

 	if (!mtd->read_oob)
 		ret = -EOPNOTSUPP;
 	else
 		ret = access_ok(VERIFY_WRITE, ptr,
 				length) ? 0 : -EFAULT;
 	if (ret)
 		return ret;

 	ops.ooblen = length;
 	ops.ooboffs = start & (mtd->oobsize - 1);
 	ops.datbuf = NULL;
 	ops.mode = MTD_OOB_PLACE;

 	if (ops.ooboffs && ops.ooblen > (mtd->oobsize - ops.ooboffs))
 		return -EINVAL;

 	ops.oobbuf = kmalloc(length, GFP_KERNEL);
 	if (!ops.oobbuf)
 		return -ENOMEM;

 	start &= ~((uint64_t)mtd->oobsize - 1);
 	ret = mtd->read_oob(mtd, start, &ops);

 	if (put_user(ops.oobretlen, retp))
 		ret = -EFAULT;
 	else if (ops.oobretlen && copy_to_user(ptr, ops.oobbuf,
 					    ops.oobretlen))
 		ret = -EFAULT;

 	kfree(ops.oobbuf);
 	return ret;
 }

 static int mtd_ioctl(struct inode *inode, struct file *file,
 		     u_int cmd, u_long arg)
 {
 	struct mtd_file_info *mfi = file->private_data;
 	struct mtd_info *mtd = mfi->mtd;
 	void __user *argp = (void __user *)arg;
 	int ret = 0;
 	u_long size;
 	struct mtd_info_user info;

 	DEBUG(MTD_DEBUG_LEVEL0, "MTD_ioctl\n");

 	size = (cmd & IOCSIZE_MASK) >> IOCSIZE_SHIFT;
 	if (cmd & IOC_IN) {
 		if (!access_ok(VERIFY_READ, argp, size))
 			return -EFAULT;
 	}
 	if (cmd & IOC_OUT) {
 		if (!access_ok(VERIFY_WRITE, argp, size))
 			return -EFAULT;
 	}

 	switch (cmd) {
 	case MEMGETREGIONCOUNT:
 		if (copy_to_user(argp, &(mtd->numeraseregions), sizeof(int)))
 			return -EFAULT;
 		break;

 	case MEMGETREGIONINFO:
 	{
 		uint32_t ur_idx;
 		struct mtd_erase_region_info *kr;
 		struct region_info_user __user *ur = argp;

 		if (get_user(ur_idx, &(ur->regionindex)))
 			return -EFAULT;

 		kr = &(mtd->eraseregions[ur_idx]);

 		if (put_user(kr->offset, &(ur->offset))
 		    || put_user(kr->erasesize, &(ur->erasesize))
 		    || put_user(kr->numblocks, &(ur->numblocks)))
 			return -EFAULT;

 		break;
 	}

 	case MEMGETINFO:
 		info.type	= mtd->type;
 		info.flags	= mtd->flags;
 		info.size	= mtd->size;
 		info.erasesize	= mtd->erasesize;
 		info.writesize	= mtd->writesize;
 		info.oobsize	= mtd->oobsize;
 		/* The below fields are obsolete */
 		info.ecctype	= -1;
 		info.eccsize	= 0;
 		if (copy_to_user(argp, &info, sizeof(struct mtd_info_user)))
 			return -EFAULT;
 		break;

 	case MEMERASE:
 	case MEMERASE64:
 	{
 		struct erase_info *erase;

 		if(!(file->f_mode & FMODE_WRITE))
 			return -EPERM;

 		erase=kzalloc(sizeof(struct erase_info),GFP_KERNEL);
 		if (!erase)
 			ret = -ENOMEM;
 		else {
 			wait_queue_head_t waitq;
 			DECLARE_WAITQUEUE(wait, current);

 			init_waitqueue_head(&waitq);

 			if (cmd == MEMERASE64) {
 				struct erase_info_user64 einfo64;

 				if (copy_from_user(&einfo64, argp,
 					    sizeof(struct erase_info_user64))) {
 					kfree(erase);
 					return -EFAULT;
 				}
 				erase->addr = einfo64.start;
 				erase->len = einfo64.length;
 			} else {
 				struct erase_info_user einfo32;

 				if (copy_from_user(&einfo32, argp,
 					    sizeof(struct erase_info_user))) {
 					kfree(erase);
 					return -EFAULT;
 				}
 				erase->addr = einfo32.start;
 				erase->len = einfo32.length;
 			}
 			erase->mtd = mtd;
 			erase->callback = mtdchar_erase_callback;
 			erase->priv = (unsigned long)&waitq;

 			/*
 			  FIXME: Allow INTERRUPTIBLE. Which means
 			  not having the wait_queue head on the stack.

 			  If the wq_head is on the stack, and we
 			  leave because we got interrupted, then the
 			  wq_head is no longer there when the
 			  callback routine tries to wake us up.
 			*/
 			ret = mtd->erase(mtd, erase);
 			if (!ret) {
 				set_current_state(TASK_UNINTERRUPTIBLE);
 				add_wait_queue(&waitq, &wait);
 				if (erase->state != MTD_ERASE_DONE &&
 				    erase->state != MTD_ERASE_FAILED)
 					schedule();
 				remove_wait_queue(&waitq, &wait);
 				set_current_state(TASK_RUNNING);

 				ret = (erase->state == MTD_ERASE_FAILED)?-EIO:0;
 			}
 			kfree(erase);
 		}
 		break;
 	}

 	case MEMWRITEOOB:
 	{
 		struct mtd_oob_buf buf;
 		struct mtd_oob_buf __user *buf_user = argp;

 		/* NOTE: writes return length to buf_user->length */
 		if (copy_from_user(&buf, argp, sizeof(buf)))
 			ret = -EFAULT;
 		else
 			ret = mtd_do_writeoob(file, mtd, buf.start, buf.length,
 				buf.ptr, &buf_user->length);
 		break;
 	}

 	case MEMREADOOB:
 	{
 		struct mtd_oob_buf buf;
 		struct mtd_oob_buf __user *buf_user = argp;

 		/* NOTE: writes return length to buf_user->start */
 		if (copy_from_user(&buf, argp, sizeof(buf)))
 			ret = -EFAULT;
 		else
 			ret = mtd_do_readoob(mtd, buf.start, buf.length,
 				buf.ptr, &buf_user->start);
 		break;
 	}

 	case MEMWRITEOOB64:
 	{
 		struct mtd_oob_buf64 buf;
 		struct mtd_oob_buf64 __user *buf_user = argp;

 		if (copy_from_user(&buf, argp, sizeof(buf)))
 			ret = -EFAULT;
 		else
 			ret = mtd_do_writeoob(file, mtd, buf.start, buf.length,
 				(void __user *)(uintptr_t)buf.usr_ptr,
 				&buf_user->length);
 		break;
 	}

 	case MEMREADOOB64:
 	{
 		struct mtd_oob_buf64 buf;
 		struct mtd_oob_buf64 __user *buf_user = argp;

 		if (copy_from_user(&buf, argp, sizeof(buf)))
 			ret = -EFAULT;
 		else
 			ret = mtd_do_readoob(mtd, buf.start, buf.length,
 				(void __user *)(uintptr_t)buf.usr_ptr,
 				&buf_user->length);
 		break;
 	}

 	case MEMLOCK:
 	{
 		struct erase_info_user einfo;

 		if (copy_from_user(&einfo, argp, sizeof(einfo)))
 			return -EFAULT;

 		if (!mtd->lock)
 			ret = -EOPNOTSUPP;
 		else
 			ret = mtd->lock(mtd, einfo.start, einfo.length);
 		break;
 	}

 	case MEMUNLOCK:
 	{
 		struct erase_info_user einfo;

 		if (copy_from_user(&einfo, argp, sizeof(einfo)))
 			return -EFAULT;

 		if (!mtd->unlock)
 			ret = -EOPNOTSUPP;
 		else
 			ret = mtd->unlock(mtd, einfo.start, einfo.length);
 		break;
 	}

 	/* Legacy interface */
 	case MEMGETOOBSEL:
 	{
 		struct nand_oobinfo oi;

 		if (!mtd->ecclayout)
 			return -EOPNOTSUPP;
 		if (mtd->ecclayout->eccbytes > ARRAY_SIZE(oi.eccpos))
 			return -EINVAL;

 		oi.useecc = MTD_NANDECC_AUTOPLACE;
 		memcpy(&oi.eccpos, mtd->ecclayout->eccpos, sizeof(oi.eccpos));
 		memcpy(&oi.oobfree, mtd->ecclayout->oobfree,
 		       sizeof(oi.oobfree));
 		oi.eccbytes = mtd->ecclayout->eccbytes;

 		if (copy_to_user(argp, &oi, sizeof(struct nand_oobinfo)))
 			return -EFAULT;
 		break;
 	}

 	case MEMGETBADBLOCK:
 	{
 		loff_t offs;

 		if (copy_from_user(&offs, argp, sizeof(loff_t)))
 			return -EFAULT;
 		if (!mtd->block_isbad)
 			ret = -EOPNOTSUPP;
 		else
 			return mtd->block_isbad(mtd, offs);
 		break;
 	}

 	case MEMSETBADBLOCK:
 	{
 		loff_t offs;

 		if (copy_from_user(&offs, argp, sizeof(loff_t)))
 			return -EFAULT;
 		if (!mtd->block_markbad)
 			ret = -EOPNOTSUPP;
 		else
 			return mtd->block_markbad(mtd, offs);
 		break;
 	}

 #ifdef CONFIG_HAVE_MTD_OTP
 	case OTPSELECT:
 	{
 		int mode;
 		if (copy_from_user(&mode, argp, sizeof(int)))
 			return -EFAULT;

 		mfi->mode = MTD_MODE_NORMAL;

 		ret = otp_select_filemode(mfi, mode);

 		file->f_pos = 0;
 		break;
 	}

 	case OTPGETREGIONCOUNT:
 	case OTPGETREGIONINFO:
 	{
 		struct otp_info *buf = kmalloc(4096, GFP_KERNEL);
 		if (!buf)
 			return -ENOMEM;
 		ret = -EOPNOTSUPP;
 		switch (mfi->mode) {
 		case MTD_MODE_OTP_FACTORY:
 			if (mtd->get_fact_prot_info)
 				ret = mtd->get_fact_prot_info(mtd, buf, 4096);
 			break;
 		case MTD_MODE_OTP_USER:
 			if (mtd->get_user_prot_info)
 				ret = mtd->get_user_prot_info(mtd, buf, 4096);
 			break;
 		default:
 			break;
 		}
 		if (ret >= 0) {
 			if (cmd == OTPGETREGIONCOUNT) {
 				int nbr = ret / sizeof(struct otp_info);
 				ret = copy_to_user(argp, &nbr, sizeof(int));
 			} else
 				ret = copy_to_user(argp, buf, ret);
 			if (ret)
 				ret = -EFAULT;
 		}
 		kfree(buf);
 		break;
 	}

 	case OTPLOCK:
 	{
 		struct otp_info oinfo;

 		if (mfi->mode != MTD_MODE_OTP_USER)
 			return -EINVAL;
 		if (copy_from_user(&oinfo, argp, sizeof(oinfo)))
 			return -EFAULT;
 		if (!mtd->lock_user_prot_reg)
 			return -EOPNOTSUPP;
 		ret = mtd->lock_user_prot_reg(mtd, oinfo.start, oinfo.length);
 		break;
 	}
 #endif

 	case ECCGETLAYOUT:
 	{
 		if (!mtd->ecclayout)
 			return -EOPNOTSUPP;

 		if (copy_to_user(argp, mtd->ecclayout,
 				 sizeof(struct nand_ecclayout)))
 			return -EFAULT;
 		break;
 	}

 	case ECCGETSTATS:
 	{
 		if (copy_to_user(argp, &mtd->ecc_stats,
 				 sizeof(struct mtd_ecc_stats)))
 			return -EFAULT;
 		break;
 	}

 	case MTDFILEMODE:
 	{
 		mfi->mode = 0;

 		switch(arg) {
 		case MTD_MODE_OTP_FACTORY:
 		case MTD_MODE_OTP_USER:
 			ret = otp_select_filemode(mfi, arg);
 			break;

 		case MTD_MODE_RAW:
 			if (!mtd->read_oob || !mtd->write_oob)
 				return -EOPNOTSUPP;
 			mfi->mode = arg;

 		case MTD_MODE_NORMAL:
 			break;
 		default:
 			ret = -EINVAL;
 		}
 		file->f_pos = 0;
 		break;
 	}

 	default:
 		ret = -ENOTTY;
 	}

 	return ret;
 } /* memory_ioctl */

 #ifdef CONFIG_COMPAT

 struct mtd_oob_buf32 {
 	u_int32_t start;
 	u_int32_t length;
 	compat_caddr_t ptr;	/* unsigned char* */
 };

 #define MEMWRITEOOB32		_IOWR('M', 3, struct mtd_oob_buf32)
 #define MEMREADOOB32		_IOWR('M', 4, struct mtd_oob_buf32)

 static long mtd_compat_ioctl(struct file *file, unsigned int cmd,
 	unsigned long arg)
 {
 	struct inode *inode = file->f_path.dentry->d_inode;
 	struct mtd_file_info *mfi = file->private_data;
 	struct mtd_info *mtd = mfi->mtd;
 	void __user *argp = compat_ptr(arg);
 	int ret = 0;

 	lock_kernel();

 	switch (cmd) {
 	case MEMWRITEOOB32:
 	{
 		struct mtd_oob_buf32 buf;
 		struct mtd_oob_buf32 __user *buf_user = argp;

 		if (copy_from_user(&buf, argp, sizeof(buf)))
 			ret = -EFAULT;
 		else
 			ret = mtd_do_writeoob(file, mtd, buf.start,
 				buf.length, compat_ptr(buf.ptr),
 				&buf_user->length);
 		break;
 	}

 	case MEMREADOOB32:
 	{
 		struct mtd_oob_buf32 buf;
 		struct mtd_oob_buf32 __user *buf_user = argp;

 		/* NOTE: writes return length to buf->start */
 		if (copy_from_user(&buf, argp, sizeof(buf)))
 			ret = -EFAULT;
 		else
 			ret = mtd_do_readoob(mtd, buf.start,
 				buf.length, compat_ptr(buf.ptr),
 				&buf_user->start);
 		break;
 	}
 	default:
 		ret = mtd_ioctl(inode, file, cmd, (unsigned long)argp);
 	}

 	unlock_kernel();

 	return ret;
 }

 #endif /* CONFIG_COMPAT */

 /*
  * try to determine where a shared mapping can be made
  * - only supported for NOMMU at the moment (MMU can't doesn't copy private
  *   mappings)
  */
 #ifndef CONFIG_MMU
 static unsigned long mtd_get_unmapped_area(struct file *file,
 					   unsigned long addr,
 					   unsigned long len,
 					   unsigned long pgoff,
 					   unsigned long flags)
 {
 	struct mtd_file_info *mfi = file->private_data;
 	struct mtd_info *mtd = mfi->mtd;

 	if (mtd->get_unmapped_area) {
 		unsigned long offset;

 		if (addr != 0)
 			return (unsigned long) -EINVAL;

 		if (len > mtd->size || pgoff >= (mtd->size >> PAGE_SHIFT))
 			return (unsigned long) -EINVAL;

 		offset = pgoff << PAGE_SHIFT;
 		if (offset > mtd->size - len)
 			return (unsigned long) -EINVAL;

 		return mtd->get_unmapped_area(mtd, len, offset, flags);
 	}

 	/* can't map directly */
 	return (unsigned long) -ENOSYS;
 }
 #endif

 /*
  * set up a mapping for shared memory segments
  */
 static int mtd_mmap(struct file *file, struct vm_area_struct *vma)
 {
 #ifdef CONFIG_MMU
 	struct mtd_file_info *mfi = file->private_data;
 	struct mtd_info *mtd = mfi->mtd;

 	if (mtd->type == MTD_RAM || mtd->type == MTD_ROM)
 		return 0;
 	return -ENOSYS;
 #else
 	return vma->vm_flags & VM_SHARED ? 0 : -ENOSYS;
 #endif
 }

 static const struct file_operations mtd_fops = {
 	.owner		= THIS_MODULE,
 	.llseek		= mtd_lseek,
 	.read		= mtd_read,
 	.write		= mtd_write,
 	.ioctl		= mtd_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= mtd_compat_ioctl,
 #endif
 	.open		= mtd_open,
 	.release	= mtd_close,
 	.mmap		= mtd_mmap,
 #ifndef CONFIG_MMU
 	.get_unmapped_area = mtd_get_unmapped_area,
 #endif
 };

 static int mtd_inodefs_get_sb(struct file_system_type *fs_type, int flags,
                                const char *dev_name, void *data,
                                struct vfsmount *mnt)
 {
         return get_sb_pseudo(fs_type, "mtd_inode:", NULL, MTD_INODE_FS_MAGIC,
                              mnt);
 }

 static struct file_system_type mtd_inodefs_type = {
        .name = "mtd_inodefs",
        .get_sb = mtd_inodefs_get_sb,
        .kill_sb = kill_anon_super,
 };

 static void mtdchar_notify_add(struct mtd_info *mtd)
 {
 }

 static void mtdchar_notify_remove(struct mtd_info *mtd)
 {
 	struct inode *mtd_ino = ilookup(mtd_inode_mnt->mnt_sb, mtd->index);

 	if (mtd_ino) {
 		/* Destroy the inode if it exists */
 		mtd_ino->i_nlink = 0;
 		iput(mtd_ino);
 	}
 }

 static struct mtd_notifier mtdchar_notifier = {
 	.add = mtdchar_notify_add,
 	.remove = mtdchar_notify_remove,
 };

 static int __init init_mtdchar(void)
 {
 	int ret;

 	ret = __register_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS,
 				   "mtd", &mtd_fops);
 	if (ret < 0) {
 		pr_notice("Can't allocate major number %d for "
 				"Memory Technology Devices.\n", MTD_CHAR_MAJOR);
 		return ret;
 	}

 	ret = register_filesystem(&mtd_inodefs_type);
 	if (ret) {
 		pr_notice("Can't register mtd_inodefs filesystem: %d\n", ret);
 		goto err_unregister_chdev;
 	}

 	mtd_inode_mnt = kern_mount(&mtd_inodefs_type);
 	if (IS_ERR(mtd_inode_mnt)) {
 		ret = PTR_ERR(mtd_inode_mnt);
 		pr_notice("Error mounting mtd_inodefs filesystem: %d\n", ret);
 		goto err_unregister_filesystem;
 	}
 	register_mtd_user(&mtdchar_notifier);

 	return ret;

 err_unregister_filesystem:
 	unregister_filesystem(&mtd_inodefs_type);
 err_unregister_chdev:
 	__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
 	return ret;
 }

 static void __exit cleanup_mtdchar(void)
 {
 	unregister_mtd_user(&mtdchar_notifier);
 	mntput(mtd_inode_mnt);
 	unregister_filesystem(&mtd_inodefs_type);
 	__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
 }

 module_init(init_mtdchar);
 module_exit(cleanup_mtdchar);

 MODULE_ALIAS_CHARDEV_MAJOR(MTD_CHAR_MAJOR);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 MODULE_DESCRIPTION("Direct character-device access to MTD devices");
 MODULE_ALIAS_CHARDEV_MAJOR(MTD_CHAR_MAJOR);
	/*
	* Character-device access to raw MTD devices.
	*
	*/

	#include <linux/device.h>
	#include <linux/fs.h>
	#include <linux/mm.h>
	#include <linux/err.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/sched.h>
	#include <linux/smp_lock.h>
	#include <linux/backing-dev.h>
	#include <linux/compat.h>
	#include <linux/mount.h>

	#include <linux/mtd/mtd.h>
	#include <linux/mtd/compatmac.h>

	#include <asm/uaccess.h>

	#define MTD_INODE_FS_MAGIC 0x11307854
	static struct vfsmount *mtd_inode_mnt __read_mostly;

	/*
	* Data structure to hold the pointer to the mtd device as well
	* as mode information ofr various use cases.
	*/
	struct mtd_file_info {
	struct mtd_info *mtd;
	struct inode *ino;
	enum mtd_file_modes mode;
	};

	static loff_t mtd_lseek (struct file *file, loff_t offset, int orig)
	{
	struct mtd_file_info *mfi = file->private_data;
	struct mtd_info *mtd = mfi->mtd;

	switch (orig) {
	case SEEK_SET:
	break;
	case SEEK_CUR:
	offset += file->f_pos;
	break;
	case SEEK_END:
	offset += mtd->size;
	break;
	default:
	return -EINVAL;
	}

	if (offset >= 0 && offset <= mtd->size)
	return file->f_pos = offset;

	return -EINVAL;
	}



	static int mtd_open(struct inode inode, struct file file)
	{
	int minor = iminor(inode);
	int devnum = minor >> 1;
	int ret = 0;
	struct mtd_info *mtd;
	struct mtd_file_info *mfi;
	struct inode *mtd_ino;

	DEBUG(MTD_DEBUG_LEVEL0, "MTD_open\n");

	/* You can't open the RO devices RW */
	if ((file->f_mode & FMODE_WRITE) && (minor & 1))
	return -EACCES;

	lock_kernel();
	mtd = get_mtd_device(NULL, devnum);

	if (IS_ERR(mtd)) {
	ret = PTR_ERR(mtd);
	goto out;
	}

	if (mtd->type == MTD_ABSENT) {
	put_mtd_device(mtd);
	ret = -ENODEV;
	goto out;
	}

	mtd_ino = iget_locked(mtd_inode_mnt->mnt_sb, devnum);
	if (!mtd_ino) {
	put_mtd_device(mtd);
	ret = -ENOMEM;
	goto out;
	}
	if (mtd_ino->i_state & I_NEW) {
	mtd_ino->i_private = mtd;
	mtd_ino->i_mode = S_IFCHR;
	mtd_ino->i_data.backing_dev_info = mtd->backing_dev_info;
	unlock_new_inode(mtd_ino);
	}
	file->f_mapping = mtd_ino->i_mapping;

	/* You can't open it RW if it's not a writeable device */
	if ((file->f_mode & FMODE_WRITE) && !(mtd->flags & MTD_WRITEABLE)) {
	iput(mtd_ino);
	put_mtd_device(mtd);
	ret = -EACCES;
	goto out;
	}

	mfi = kzalloc(sizeof(*mfi), GFP_KERNEL);
	if (!mfi) {
	iput(mtd_ino);
	put_mtd_device(mtd);
	ret = -ENOMEM;
	goto out;
	}
	mfi->ino = mtd_ino;
	mfi->mtd = mtd;
	file->private_data = mfi;

	out:
	unlock_kernel();
	return ret;
	} /* mtd_open */

	/====================================================================/

	static int mtd_close(struct inode inode, struct file file)
	{
	struct mtd_file_info *mfi = file->private_data;
	struct mtd_info *mtd = mfi->mtd;

	DEBUG(MTD_DEBUG_LEVEL0, "MTD_close\n");

	/* Only sync if opened RW */
	if ((file->f_mode & FMODE_WRITE) && mtd->sync)
	mtd->sync(mtd);

	iput(mfi->ino);

	put_mtd_device(mtd);
	file->private_data = NULL;
	kfree(mfi);

	return 0;
	} /* mtd_close */

	/* FIXME: This _really_ needs to die. In 2.5, we should lock the
	userspace buffer down and use it directly with readv/writev.
	*/
	#define MAX_KMALLOC_SIZE 0x20000

	static ssize_t mtd_read(struct file file, char __user buf, size_t count,loff_t *ppos)
	{
	struct mtd_file_info *mfi = file->private_data;
	struct mtd_info *mtd = mfi->mtd;
	size_t retlen=0;
	size_t total_retlen=0;
	int ret=0;
	int len;
	char *kbuf;

	DEBUG(MTD_DEBUG_LEVEL0,"MTD_read\n");

	if (*ppos + count > mtd->size)
	count = mtd->size - *ppos;

	if (!count)
	return 0;

	/* FIXME: Use kiovec in 2.5 to lock down the user's buffers
	and pass them directly to the MTD functions */

	if (count > MAX_KMALLOC_SIZE)
	kbuf=kmalloc(MAX_KMALLOC_SIZE, GFP_KERNEL);
	else
	kbuf=kmalloc(count, GFP_KERNEL);

	if (!kbuf)
	return -ENOMEM;

	while (count) {

	if (count > MAX_KMALLOC_SIZE)
	len = MAX_KMALLOC_SIZE;
	else
	len = count;

	switch (mfi->mode) {
	case MTD_MODE_OTP_FACTORY:
	ret = mtd->read_fact_prot_reg(mtd, *ppos, len, &retlen, kbuf);
	break;
	case MTD_MODE_OTP_USER:
	ret = mtd->read_user_prot_reg(mtd, *ppos, len, &retlen, kbuf);
	break;
	case MTD_MODE_RAW:
	{
	struct mtd_oob_ops ops;

	ops.mode = MTD_OOB_RAW;
	ops.datbuf = kbuf;
	ops.oobbuf = NULL;
	ops.len = len;

	ret = mtd->read_oob(mtd, *ppos, &ops);
	retlen = ops.retlen;
	break;
	}
	default:
	ret = mtd->read(mtd, *ppos, len, &retlen, kbuf);
	}
	/* Nand returns -EBADMSG on ecc errors, but it returns
	* the data. For our userspace tools it is important
	* to dump areas with ecc errors !
	* For kernel internal usage it also might return -EUCLEAN
	* to signal the caller that a bitflip has occured and has
	* been corrected by the ECC algorithm.
	* Userspace software which accesses NAND this way
	* must be aware of the fact that it deals with NAND
	*/
	if (!ret \|\| (ret == -EUCLEAN) \|\| (ret == -EBADMSG)) {
	*ppos += retlen;
	if (copy_to_user(buf, kbuf, retlen)) {
	kfree(kbuf);
	return -EFAULT;
	}
	else
	total_retlen += retlen;

	count -= retlen;
	buf += retlen;
	if (retlen == 0)
	count = 0;
	}
	else {
	kfree(kbuf);
	return ret;
	}

	}

	kfree(kbuf);
	return total_retlen;
	} /* mtd_read */

	static ssize_t mtd_write(struct file file, const char __user buf, size_t count,loff_t *ppos)
	{
	struct mtd_file_info *mfi = file->private_data;
	struct mtd_info *mtd = mfi->mtd;
	char *kbuf;
	size_t retlen;
	size_t total_retlen=0;
	int ret=0;
	int len;

	DEBUG(MTD_DEBUG_LEVEL0,"MTD_write\n");

	if (*ppos == mtd->size)
	return -ENOSPC;

	if (*ppos + count > mtd->size)
	count = mtd->size - *ppos;

	if (!count)
	return 0;

	if (count > MAX_KMALLOC_SIZE)
	kbuf=kmalloc(MAX_KMALLOC_SIZE, GFP_KERNEL);
	else
	kbuf=kmalloc(count, GFP_KERNEL);

	if (!kbuf)
	return -ENOMEM;

	while (count) {

	if (count > MAX_KMALLOC_SIZE)
	len = MAX_KMALLOC_SIZE;
	else
	len = count;

	if (copy_from_user(kbuf, buf, len)) {
	kfree(kbuf);
	return -EFAULT;
	}

	switch (mfi->mode) {
	case MTD_MODE_OTP_FACTORY:
	ret = -EROFS;
	break;
	case MTD_MODE_OTP_USER:
	if (!mtd->write_user_prot_reg) {
	ret = -EOPNOTSUPP;
	break;
	}
	ret = mtd->write_user_prot_reg(mtd, *ppos, len, &retlen, kbuf);
	break;

	case MTD_MODE_RAW:
	{
	struct mtd_oob_ops ops;

	ops.mode = MTD_OOB_RAW;
	ops.datbuf = kbuf;
	ops.oobbuf = NULL;
	ops.len = len;

	ret = mtd->write_oob(mtd, *ppos, &ops);
	retlen = ops.retlen;
	break;
	}

	default:
	ret = ((mtd->write))(mtd, ppos, len, &retlen, kbuf);
	}
	if (!ret) {
	*ppos += retlen;
	total_retlen += retlen;
	count -= retlen;
	buf += retlen;
	}
	else {
	kfree(kbuf);
	return ret;
	}
	}

	kfree(kbuf);
	return total_retlen;
	} /* mtd_write */

	/*======================================================================

	IOCTL calls for getting device parameters.

	======================================================================*/
	static void mtdchar_erase_callback (struct erase_info *instr)
	{
	wake_up((wait_queue_head_t *)instr->priv);
	}

	#ifdef CONFIG_HAVE_MTD_OTP
	static int otp_select_filemode(struct mtd_file_info *mfi, int mode)
	{
	struct mtd_info *mtd = mfi->mtd;
	int ret = 0;

	switch (mode) {
	case MTD_OTP_FACTORY:
	if (!mtd->read_fact_prot_reg)
	ret = -EOPNOTSUPP;
	else
	mfi->mode = MTD_MODE_OTP_FACTORY;
	break;
	case MTD_OTP_USER:
	if (!mtd->read_fact_prot_reg)
	ret = -EOPNOTSUPP;
	else
	mfi->mode = MTD_MODE_OTP_USER;
	break;
	default:
	ret = -EINVAL;
	case MTD_OTP_OFF:
	break;
	}
	return ret;
	}
	#else
	# define otp_select_filemode(f,m) -EOPNOTSUPP
	#endif

	static int mtd_do_writeoob(struct file file, struct mtd_info mtd,
	uint64_t start, uint32_t length, void __user *ptr,
	uint32_t __user *retp)
	{
	struct mtd_oob_ops ops;
	uint32_t retlen;
	int ret = 0;

	if (!(file->f_mode & FMODE_WRITE))
	return -EPERM;

	if (length > 4096)
	return -EINVAL;

	if (!mtd->write_oob)
	ret = -EOPNOTSUPP;
	else
	ret = access_ok(VERIFY_READ, ptr, length) ? 0 : -EFAULT;

	if (ret)
	return ret;

	ops.ooblen = length;
	ops.ooboffs = start & (mtd->oobsize - 1);
	ops.datbuf = NULL;
	ops.mode = MTD_OOB_PLACE;

	if (ops.ooboffs && ops.ooblen > (mtd->oobsize - ops.ooboffs))
	return -EINVAL;

	ops.oobbuf = kmalloc(length, GFP_KERNEL);
	if (!ops.oobbuf)
	return -ENOMEM;

	if (copy_from_user(ops.oobbuf, ptr, length)) {
	kfree(ops.oobbuf);
	return -EFAULT;
	}

	start &= ~((uint64_t)mtd->oobsize - 1);
	ret = mtd->write_oob(mtd, start, &ops);

	if (ops.oobretlen > 0xFFFFFFFFU)
	ret = -EOVERFLOW;
	retlen = ops.oobretlen;
	if (copy_to_user(retp, &retlen, sizeof(length)))
	ret = -EFAULT;

	kfree(ops.oobbuf);
	return ret;
	}

	static int mtd_do_readoob(struct mtd_info *mtd, uint64_t start,
	uint32_t length, void __user ptr, uint32_t __user retp)
	{
	struct mtd_oob_ops ops;
	int ret = 0;

	if (length > 4096)
	return -EINVAL;

	if (!mtd->read_oob)
	ret = -EOPNOTSUPP;
	else
	ret = access_ok(VERIFY_WRITE, ptr,
	length) ? 0 : -EFAULT;
	if (ret)
	return ret;

	ops.ooblen = length;
	ops.ooboffs = start & (mtd->oobsize - 1);
	ops.datbuf = NULL;
	ops.mode = MTD_OOB_PLACE;

	if (ops.ooboffs && ops.ooblen > (mtd->oobsize - ops.ooboffs))
	return -EINVAL;

	ops.oobbuf = kmalloc(length, GFP_KERNEL);
	if (!ops.oobbuf)
	return -ENOMEM;

	start &= ~((uint64_t)mtd->oobsize - 1);
	ret = mtd->read_oob(mtd, start, &ops);

	if (put_user(ops.oobretlen, retp))
	ret = -EFAULT;
	else if (ops.oobretlen && copy_to_user(ptr, ops.oobbuf,
	ops.oobretlen))
	ret = -EFAULT;

	kfree(ops.oobbuf);
	return ret;
	}

	static int mtd_ioctl(struct inode inode, struct file file,
	u_int cmd, u_long arg)
	{
	struct mtd_file_info *mfi = file->private_data;
	struct mtd_info *mtd = mfi->mtd;
	void __user argp = (void __user )arg;
	int ret = 0;
	u_long size;
	struct mtd_info_user info;

	DEBUG(MTD_DEBUG_LEVEL0, "MTD_ioctl\n");

	size = (cmd & IOCSIZE_MASK) >> IOCSIZE_SHIFT;
	if (cmd & IOC_IN) {
	if (!access_ok(VERIFY_READ, argp, size))
	return -EFAULT;
	}
	if (cmd & IOC_OUT) {
	if (!access_ok(VERIFY_WRITE, argp, size))
	return -EFAULT;
	}

	switch (cmd) {
	case MEMGETREGIONCOUNT:
	if (copy_to_user(argp, &(mtd->numeraseregions), sizeof(int)))
	return -EFAULT;
	break;

	case MEMGETREGIONINFO:
	{
	uint32_t ur_idx;
	struct mtd_erase_region_info *kr;
	struct region_info_user __user *ur = argp;

	if (get_user(ur_idx, &(ur->regionindex)))
	return -EFAULT;

	kr = &(mtd->eraseregions[ur_idx]);

	if (put_user(kr->offset, &(ur->offset))
	\|\| put_user(kr->erasesize, &(ur->erasesize))
	\|\| put_user(kr->numblocks, &(ur->numblocks)))
	return -EFAULT;

	break;
	}

	case MEMGETINFO:
	info.type = mtd->type;
	info.flags = mtd->flags;
	info.size = mtd->size;
	info.erasesize = mtd->erasesize;
	info.writesize = mtd->writesize;
	info.oobsize = mtd->oobsize;
	/* The below fields are obsolete */
	info.ecctype = -1;
	info.eccsize = 0;
	if (copy_to_user(argp, &info, sizeof(struct mtd_info_user)))
	return -EFAULT;
	break;

	case MEMERASE:
	case MEMERASE64:
	{
	struct erase_info *erase;

	if(!(file->f_mode & FMODE_WRITE))
	return -EPERM;

	erase=kzalloc(sizeof(struct erase_info),GFP_KERNEL);
	if (!erase)
	ret = -ENOMEM;
	else {
	wait_queue_head_t waitq;
	DECLARE_WAITQUEUE(wait, current);

	init_waitqueue_head(&waitq);

	if (cmd == MEMERASE64) {
	struct erase_info_user64 einfo64;

	if (copy_from_user(&einfo64, argp,
	sizeof(struct erase_info_user64))) {
	kfree(erase);
	return -EFAULT;
	}
	erase->addr = einfo64.start;
	erase->len = einfo64.length;
	} else {
	struct erase_info_user einfo32;

	if (copy_from_user(&einfo32, argp,
	sizeof(struct erase_info_user))) {
	kfree(erase);
	return -EFAULT;
	}
	erase->addr = einfo32.start;
	erase->len = einfo32.length;
	}
	erase->mtd = mtd;
	erase->callback = mtdchar_erase_callback;
	erase->priv = (unsigned long)&waitq;

	/*
	FIXME: Allow INTERRUPTIBLE. Which means
	not having the wait_queue head on the stack.

	If the wq_head is on the stack, and we
	leave because we got interrupted, then the
	wq_head is no longer there when the
	callback routine tries to wake us up.
	*/
	ret = mtd->erase(mtd, erase);
	if (!ret) {
	set_current_state(TASK_UNINTERRUPTIBLE);
	add_wait_queue(&waitq, &wait);
	if (erase->state != MTD_ERASE_DONE &&
	erase->state != MTD_ERASE_FAILED)
	schedule();
	remove_wait_queue(&waitq, &wait);
	set_current_state(TASK_RUNNING);

	ret = (erase->state == MTD_ERASE_FAILED)?-EIO:0;
	}
	kfree(erase);
	}
	break;
	}

	case MEMWRITEOOB:
	{
	struct mtd_oob_buf buf;
	struct mtd_oob_buf __user *buf_user = argp;

	/* NOTE: writes return length to buf_user->length */
	if (copy_from_user(&buf, argp, sizeof(buf)))
	ret = -EFAULT;
	else
	ret = mtd_do_writeoob(file, mtd, buf.start, buf.length,
	buf.ptr, &buf_user->length);
	break;
	}

	case MEMREADOOB:
	{
	struct mtd_oob_buf buf;
	struct mtd_oob_buf __user *buf_user = argp;

	/* NOTE: writes return length to buf_user->start */
	if (copy_from_user(&buf, argp, sizeof(buf)))
	ret = -EFAULT;
	else
	ret = mtd_do_readoob(mtd, buf.start, buf.length,
	buf.ptr, &buf_user->start);
	break;
	}

	case MEMWRITEOOB64:
	{
	struct mtd_oob_buf64 buf;
	struct mtd_oob_buf64 __user *buf_user = argp;

	if (copy_from_user(&buf, argp, sizeof(buf)))
	ret = -EFAULT;
	else
	ret = mtd_do_writeoob(file, mtd, buf.start, buf.length,
	(void __user *)(uintptr_t)buf.usr_ptr,
	&buf_user->length);
	break;
	}

	case MEMREADOOB64:
	{
	struct mtd_oob_buf64 buf;
	struct mtd_oob_buf64 __user *buf_user = argp;

	if (copy_from_user(&buf, argp, sizeof(buf)))
	ret = -EFAULT;
	else
	ret = mtd_do_readoob(mtd, buf.start, buf.length,
	(void __user *)(uintptr_t)buf.usr_ptr,
	&buf_user->length);
	break;
	}

	case MEMLOCK:
	{
	struct erase_info_user einfo;

	if (copy_from_user(&einfo, argp, sizeof(einfo)))
	return -EFAULT;

	if (!mtd->lock)
	ret = -EOPNOTSUPP;
	else
	ret = mtd->lock(mtd, einfo.start, einfo.length);
	break;
	}

	case MEMUNLOCK:
	{
	struct erase_info_user einfo;

	if (copy_from_user(&einfo, argp, sizeof(einfo)))
	return -EFAULT;

	if (!mtd->unlock)
	ret = -EOPNOTSUPP;
	else
	ret = mtd->unlock(mtd, einfo.start, einfo.length);
	break;
	}

	/* Legacy interface */
	case MEMGETOOBSEL:
	{
	struct nand_oobinfo oi;

	if (!mtd->ecclayout)
	return -EOPNOTSUPP;
	if (mtd->ecclayout->eccbytes > ARRAY_SIZE(oi.eccpos))
	return -EINVAL;

	oi.useecc = MTD_NANDECC_AUTOPLACE;
	memcpy(&oi.eccpos, mtd->ecclayout->eccpos, sizeof(oi.eccpos));
	memcpy(&oi.oobfree, mtd->ecclayout->oobfree,
	sizeof(oi.oobfree));
	oi.eccbytes = mtd->ecclayout->eccbytes;

	if (copy_to_user(argp, &oi, sizeof(struct nand_oobinfo)))
	return -EFAULT;
	break;
	}

	case MEMGETBADBLOCK:
	{
	loff_t offs;

	if (copy_from_user(&offs, argp, sizeof(loff_t)))
	return -EFAULT;
	if (!mtd->block_isbad)
	ret = -EOPNOTSUPP;
	else
	return mtd->block_isbad(mtd, offs);
	break;
	}

	case MEMSETBADBLOCK:
	{
	loff_t offs;

	if (copy_from_user(&offs, argp, sizeof(loff_t)))
	return -EFAULT;
	if (!mtd->block_markbad)
	ret = -EOPNOTSUPP;
	else
	return mtd->block_markbad(mtd, offs);
	break;
	}

	#ifdef CONFIG_HAVE_MTD_OTP
	case OTPSELECT:
	{
	int mode;
	if (copy_from_user(&mode, argp, sizeof(int)))
	return -EFAULT;

	mfi->mode = MTD_MODE_NORMAL;

	ret = otp_select_filemode(mfi, mode);

	file->f_pos = 0;
	break;
	}

	case OTPGETREGIONCOUNT:
	case OTPGETREGIONINFO:
	{
	struct otp_info *buf = kmalloc(4096, GFP_KERNEL);
	if (!buf)
	return -ENOMEM;
	ret = -EOPNOTSUPP;
	switch (mfi->mode) {
	case MTD_MODE_OTP_FACTORY:
	if (mtd->get_fact_prot_info)
	ret = mtd->get_fact_prot_info(mtd, buf, 4096);
	break;
	case MTD_MODE_OTP_USER:
	if (mtd->get_user_prot_info)
	ret = mtd->get_user_prot_info(mtd, buf, 4096);
	break;
	default:
	break;
	}
	if (ret >= 0) {
	if (cmd == OTPGETREGIONCOUNT) {
	int nbr = ret / sizeof(struct otp_info);
	ret = copy_to_user(argp, &nbr, sizeof(int));
	} else
	ret = copy_to_user(argp, buf, ret);
	if (ret)
	ret = -EFAULT;
	}
	kfree(buf);
	break;
	}

	case OTPLOCK:
	{
	struct otp_info oinfo;

	if (mfi->mode != MTD_MODE_OTP_USER)
	return -EINVAL;
	if (copy_from_user(&oinfo, argp, sizeof(oinfo)))
	return -EFAULT;
	if (!mtd->lock_user_prot_reg)
	return -EOPNOTSUPP;
	ret = mtd->lock_user_prot_reg(mtd, oinfo.start, oinfo.length);
	break;
	}
	#endif

	case ECCGETLAYOUT:
	{
	if (!mtd->ecclayout)
	return -EOPNOTSUPP;

	if (copy_to_user(argp, mtd->ecclayout,
	sizeof(struct nand_ecclayout)))
	return -EFAULT;
	break;
	}

	case ECCGETSTATS:
	{
	if (copy_to_user(argp, &mtd->ecc_stats,
	sizeof(struct mtd_ecc_stats)))
	return -EFAULT;
	break;
	}

	case MTDFILEMODE:
	{
	mfi->mode = 0;

	switch(arg) {
	case MTD_MODE_OTP_FACTORY:
	case MTD_MODE_OTP_USER:
	ret = otp_select_filemode(mfi, arg);
	break;

	case MTD_MODE_RAW:
	if (!mtd->read_oob \|\| !mtd->write_oob)
	return -EOPNOTSUPP;
	mfi->mode = arg;

	case MTD_MODE_NORMAL:
	break;
	default:
	ret = -EINVAL;
	}
	file->f_pos = 0;
	break;
	}

	default:
	ret = -ENOTTY;
	}

	return ret;
	} /* memory_ioctl */

	#ifdef CONFIG_COMPAT

	struct mtd_oob_buf32 {
	u_int32_t start;
	u_int32_t length;
	compat_caddr_t ptr; /* unsigned char* */
	};

	#define MEMWRITEOOB32 _IOWR('M', 3, struct mtd_oob_buf32)
	#define MEMREADOOB32 _IOWR('M', 4, struct mtd_oob_buf32)

	static long mtd_compat_ioctl(struct file *file, unsigned int cmd,
	unsigned long arg)
	{
	struct inode *inode = file->f_path.dentry->d_inode;
	struct mtd_file_info *mfi = file->private_data;
	struct mtd_info *mtd = mfi->mtd;
	void __user *argp = compat_ptr(arg);
	int ret = 0;

	lock_kernel();

	switch (cmd) {
	case MEMWRITEOOB32:
	{
	struct mtd_oob_buf32 buf;
	struct mtd_oob_buf32 __user *buf_user = argp;

	if (copy_from_user(&buf, argp, sizeof(buf)))
	ret = -EFAULT;
	else
	ret = mtd_do_writeoob(file, mtd, buf.start,
	buf.length, compat_ptr(buf.ptr),
	&buf_user->length);
	break;
	}

	case MEMREADOOB32:
	{
	struct mtd_oob_buf32 buf;
	struct mtd_oob_buf32 __user *buf_user = argp;

	/* NOTE: writes return length to buf->start */
	if (copy_from_user(&buf, argp, sizeof(buf)))
	ret = -EFAULT;
	else
	ret = mtd_do_readoob(mtd, buf.start,
	buf.length, compat_ptr(buf.ptr),
	&buf_user->start);
	break;
	}
	default:
	ret = mtd_ioctl(inode, file, cmd, (unsigned long)argp);
	}

	unlock_kernel();

	return ret;
	}

	#endif /* CONFIG_COMPAT */

	/*
	* try to determine where a shared mapping can be made
	* - only supported for NOMMU at the moment (MMU can't doesn't copy private
	* mappings)
	*/
	#ifndef CONFIG_MMU
	static unsigned long mtd_get_unmapped_area(struct file *file,
	unsigned long addr,
	unsigned long len,
	unsigned long pgoff,
	unsigned long flags)
	{
	struct mtd_file_info *mfi = file->private_data;
	struct mtd_info *mtd = mfi->mtd;

	if (mtd->get_unmapped_area) {
	unsigned long offset;

	if (addr != 0)
	return (unsigned long) -EINVAL;

	if (len > mtd->size \|\| pgoff >= (mtd->size >> PAGE_SHIFT))
	return (unsigned long) -EINVAL;

	offset = pgoff << PAGE_SHIFT;
	if (offset > mtd->size - len)
	return (unsigned long) -EINVAL;

	return mtd->get_unmapped_area(mtd, len, offset, flags);
	}

	/* can't map directly */
	return (unsigned long) -ENOSYS;
	}
	#endif

	/*
	* set up a mapping for shared memory segments
	*/
	static int mtd_mmap(struct file file, struct vm_area_struct vma)
	{
	#ifdef CONFIG_MMU
	struct mtd_file_info *mfi = file->private_data;
	struct mtd_info *mtd = mfi->mtd;

	if (mtd->type == MTD_RAM \|\| mtd->type == MTD_ROM)
	return 0;
	return -ENOSYS;
	#else
	return vma->vm_flags & VM_SHARED ? 0 : -ENOSYS;
	#endif
	}

	static const struct file_operations mtd_fops = {
	.owner = THIS_MODULE,
	.llseek = mtd_lseek,
	.read = mtd_read,
	.write = mtd_write,
	.ioctl = mtd_ioctl,
	#ifdef CONFIG_COMPAT
	.compat_ioctl = mtd_compat_ioctl,
	#endif
	.open = mtd_open,
	.release = mtd_close,
	.mmap = mtd_mmap,
	#ifndef CONFIG_MMU
	.get_unmapped_area = mtd_get_unmapped_area,
	#endif
	};

	static int mtd_inodefs_get_sb(struct file_system_type *fs_type, int flags,
	const char dev_name, void data,
	struct vfsmount *mnt)
	{
	return get_sb_pseudo(fs_type, "mtd_inode:", NULL, MTD_INODE_FS_MAGIC,
	mnt);
	}

	static struct file_system_type mtd_inodefs_type = {
	.name = "mtd_inodefs",
	.get_sb = mtd_inodefs_get_sb,
	.kill_sb = kill_anon_super,
	};

	static void mtdchar_notify_add(struct mtd_info *mtd)
	{
	}

	static void mtdchar_notify_remove(struct mtd_info *mtd)
	{
	struct inode *mtd_ino = ilookup(mtd_inode_mnt->mnt_sb, mtd->index);

	if (mtd_ino) {
	/* Destroy the inode if it exists */
	mtd_ino->i_nlink = 0;
	iput(mtd_ino);
	}
	}

	static struct mtd_notifier mtdchar_notifier = {
	.add = mtdchar_notify_add,
	.remove = mtdchar_notify_remove,
	};

	static int __init init_mtdchar(void)
	{
	int ret;

	ret = __register_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS,
	"mtd", &mtd_fops);
	if (ret < 0) {
	pr_notice("Can't allocate major number %d for "
	"Memory Technology Devices.\n", MTD_CHAR_MAJOR);
	return ret;
	}

	ret = register_filesystem(&mtd_inodefs_type);
	if (ret) {
	pr_notice("Can't register mtd_inodefs filesystem: %d\n", ret);
	goto err_unregister_chdev;
	}

	mtd_inode_mnt = kern_mount(&mtd_inodefs_type);
	if (IS_ERR(mtd_inode_mnt)) {
	ret = PTR_ERR(mtd_inode_mnt);
	pr_notice("Error mounting mtd_inodefs filesystem: %d\n", ret);
	goto err_unregister_filesystem;
	}
	register_mtd_user(&mtdchar_notifier);

	return ret;

	err_unregister_filesystem:
	unregister_filesystem(&mtd_inodefs_type);
	err_unregister_chdev:
	__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
	return ret;
	}

	static void __exit cleanup_mtdchar(void)
	{
	unregister_mtd_user(&mtdchar_notifier);
	mntput(mtd_inode_mnt);
	unregister_filesystem(&mtd_inodefs_type);
	__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
	}

	module_init(init_mtdchar);
	module_exit(cleanup_mtdchar);

	MODULE_ALIAS_CHARDEV_MAJOR(MTD_CHAR_MAJOR);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
	MODULE_DESCRIPTION("Direct character-device access to MTD devices");
	MODULE_ALIAS_CHARDEV_MAJOR(MTD_CHAR_MAJOR);